From fe26d8b7ddce8fb00a072853d938e6a612a20979 Mon Sep 17 00:00:00 2001
From: Neil Puttock <address@hidden>
Date: Thu, 16 Sep 2010 23:54:10 +0100
Subject: [PATCH] Possible fix for #372.

---
 lily/partial-iterator.cc       |   27 +++++++++++++++++++++++++++
 scm/define-music-types.scm     |    6 ++++++
 scm/ly-syntax-constructors.scm |    6 ++++--
 3 files changed, 37 insertions(+), 2 deletions(-)
 create mode 100644 lily/partial-iterator.cc

diff --git a/lily/partial-iterator.cc b/lily/partial-iterator.cc
new file mode 100644
index 0000000..bb175d4
--- /dev/null
+++ b/lily/partial-iterator.cc
@@ -0,0 +1,27 @@
+#include "context.hh"
+#include "moment.hh"
+#include "music.hh"
+#include "simple-music-iterator.hh"
+
+class Partial_iterator : public Simple_music_iterator
+{
+public:
+  DECLARE_SCHEME_CALLBACK (constructor, ());
+ protected:
+  virtual void process (Moment);
+};
+
+void
+Partial_iterator::process (Moment m)
+{
+  Moment length
+    = robust_scm2moment (get_music ()->get_property ("partial-length"),
+			 Moment (0));
+  Context *ctx = get_outlet ();
+  Moment now = ctx->now_mom ();
+  ctx->set_property ("measurePosition", (now - length).smobbed_copy ());
+
+  Simple_music_iterator::process (m);
+}
+
+IMPLEMENT_CTOR_CALLBACK (Partial_iterator);
diff --git a/scm/define-music-types.scm b/scm/define-music-types.scm
index 7f4525e..96fe7c2 100644
--- a/scm/define-music-types.scm
+++ b/scm/define-music-types.scm
@@ -349,6 +349,12 @@ Syntax: @code{\\override} [ @var{context} @code{.} ]
 	(types . (general-music break-event page-turn-event event))
 	))
 
+    (PartialSet
+     . ((description . "Create an anacrusis.")
+	(iterator-ctor . ,ly:partial-iterator::constructor)
+	(types . (general-music partial-set))
+	))
+
     (PartCombineMusic
      . ((description . "Combine two parts on a staff, either merged or
 as separate voices.")
diff --git a/scm/ly-syntax-constructors.scm b/scm/ly-syntax-constructors.scm
index decc515..d73f6b9 100644
--- a/scm/ly-syntax-constructors.scm
+++ b/scm/ly-syntax-constructors.scm
@@ -250,10 +250,12 @@ into a @code{MultiMeasureTextEvent}."
 
 (define-ly-syntax-simple (partial dur)
   "Make a partial measure."
-  (let ((mom (ly:moment-sub ZERO-MOMENT (ly:duration-length dur))))
+  (let ((mom (ly:duration-length dur)))
 
     ;; We use `descend-to-context' here instead of `context-spec-music' to
     ;; ensure \partial still works if the Timing_translator is moved
     (descend-to-context
-     (context-spec-music (make-property-set 'measurePosition mom) 'Timing)
+     (context-spec-music (make-music 'PartialSet
+				     'partial-length mom)
+			 'Timing)
      'Score)))
-- 
1.7.0.4